For instructions on excluding files from scanning, please see:
Product documentation for various versions of F-Secure products are available on the Documentation section of the website.
F-Secure Anti-Virus can detect certain compressed/archive files that have a big compression ratio (for example 1 megabyte archive or compressed file that expands into tens of megabytes of data) as 'Mail Bomb'.
This does not mean that any infection was found in those files, it's just a warning.
If you have a legitimate file detected as 'Mail Bomb', please exclude it from scanning for both On-Access and On-Demand scanners of your F-Secure Anti-Virus.